The goal of the proposed project is to use a panel of islet-specific T cell clones derived from the nonobese diabetic (NOD) mouse to learn more about the antigens on islet cells that may be involved in autoimmune diabetes. This objective will be met through three approaches: (1) analysis of islet cell molecules obtained from lysates fractionated by gel electrophoresis or from cDNA expression libraries; (2) investigation of whether anti-islet autoantibodies react to any of the T cell antigens; and (3) determination of T cell receptor gene usage by the T cell clones. Molecules isolated from islet lysates by gel electrophoresis and products obtained from cDNA libraries will be tested for antigenicity with the T cell clones. Molecules identified as being antigenic will be resolved into peptides to see if antigenic peptides can be isolated. Anti-islet antibodies will be used in functional assays to see if they affect interaction of the T cell clones with antigen. T cell receptor gene usage will be determined by phenotypic analysis of the T cell clones with anti-T cell receptor Vbeta antibodies and by sequence analysis of T cell receptor genes. Identification of autoantigens, gaining information about B and T cell interaction, and determining whether autoreactive T cells bear T cell receptors with any unique features are all goals that hold important implications for understanding of type 1 diabetes and other spontaneous models of autoimmunity.